Heat engine



HEAT ENGINE Filed Maron 27. 1930 2 subsets-Sheet l H. F. SMITH HEAT ENGINE Sept. 27, 1932.

2 Sheets-Sheevt 2v Filed March 27, 1930 m www4 Patented Sept. 27, 1932 UNITED VSTATES PATENT OFFICE HARRY F. SMITH, OF DAYTON, OHIO, ASISIGNOR T THE RESEARCH COMPANY, OF DAYTON, OHIO, A CORPORATION OF OHIO HEAT ENGINE Application illed Karch 27, 1930. Serial No. 439,377.

This invention relates to a heat engine of the closed cycle type commonly known as a hot air engine.

One of the principal objects of this invention is to provide a multicylinder heat engine of this character which is simple in construction, eiiicient and reliable .in operation, and which is small and compact while at the same time providing the desirable phase relations lo of the moving parts.

Another object of the invention is to provide a multicylinder heat engine of this character connected to an exterior power source while maintaining a fluid tight system within l5 the engine.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings, and

the appended claims.

In the drawings, in which like characters of reference designate like parts throughout the several views thereof,

Fig. 1 is a central vertical section through a multicylinder heat engine constructed in accordance with this invention, the section being taken on the plane of the line l`1 of Fig. 2; and v Fig. 2 is a central vertical section taken on the plane of the line 2-2 of Fig. 1.

Referring to the drawings which discloses a preferred embodiment of the invention, there is illustrated a four cylinder hot air engine, in which the cylinders are mounted in line. This engine comprises an engine block or casting having four cylinders formed therein designated Nos. 1, 2, 3 and 4 respectively. Integrally formed with the block 10 is a cylindrical chamber forming a crank case 11. One end of the crank case is closed by a plate 12, and the other end of the crank case is closed by a casing 13. Bolted between the crank case 11 and casing 13 is a web member 14, formed to provide a bearing 15 for one end of a crank shaft 16, the opposite end of the crank shaft being provided with a bearing 17 formed in the plate 12. As shown the crank shaft 16 is provided with f our cranks 18 thereon, which are angularly spaced ninety degrees'apart. Thus, starting from the left in Fig. 1 each crank is ninety degrees in angular advance of each subsequent crank.

Mounted within the cylinders are pistons 20 provided in the usual manner with wrist pins 21 connected to the cranks 18 byconnectin rods 22. Each piston 20 has a sliding fit wit the cylinder wall which is of such character that a restricted fluid communication is provided between the space within the crank case below the piston and the space within the cylinder above the piston. This may be conveniently accomplished by providing smooth walled pistons without the provision of piston rings.

Mounted on the upper end of the block 10 and bolted thereto is a casing having a lower plate or casting 30 separated from the block 10 by means of a heat insulating ring 31. As shown in Fig. 2, the casing is shaped as an inverted U in cross section, and extends throughout the length of the engine block. The bottom member 30 is provided with spaced openings within which are mounted thin metal displacement cylinders designated Nos. l, 2, 3 and 4, respectively, these displacement cylinders being in alignment with the corresponding piston cylinders. Operating within each displacement cylinder is a displacement member 35, which is shown as a cylindrical member having tapered ends indicated at 36. Each displacement member 35 has .a loose fit within its respective displacement cylinder so as to readily permit the passage of fluid from one end of the displacement cylinder past the displacement member to the other.

As shown, the cylinder block 10 is formed with an aligned bore 38 of somewhat larger diameter than the bore of the piston cylinder indicated at 39, with a tapered shoulder 40 therebetween. Seating on the tapered shoulder 40 and closing communication between each displacement cylinder and its aligned piston cylinder is a cylinder head 42 bolted to the block by means of bolts 43. Welded to each displacement member 35 is a rod 44 which has a slidable-substantially fluid tight fit Within the head 42,. The lower end of thev rod 44 is provided with a threaded portion 45 of reduced diameter which passes through an opening in the top of the piston 20 and is bolted thereto by means of a nut 46. Each displacement member is thus directly connected to an aligned piston Vfor simultaneous movement in the same phase.

The engine block 10 is also provided with passages connecting each displacement cylinder with an adjacent piston cylinder. Thus displacement cylinder No. 1 is. connected by means of a passage 50 with piston cylinder No. 2; displacement cylinder No. 2 is connected bv a assage 51 with a piston cylinder No. 3; disp acement cylinder No. 3 is connected by a passage 52 with piston cylinder No. 4; and displacement cylinder No. 4 is connected by a passage 53 formed in the outer wall of the casing or block with piston cylinder No. 1. To permit shorter passages to be used, the heads 41 may be broken away as indicated at 54 and 55 at points in alignment with the respective passages. The engine block 10 is also provided with a cooling jacket 57 having passages common to all the cylinders and rovided with an intake 5S for cooling liqui from any suitable source, and an otake 59. The passage 53 is separated from the cooling jacket 57 by means of webs 60 and 61 passing about one side of the casing so as to connect displacement cylinder No. 4 with piston cylinder No. 1. In this manner, it is seen that the dis lacement member in a displacement cylin er is positioned ninety degrees in angular advance of a piston in the piston cylinder which communicates with that particular displacement cylinder, this being the preferred phase relationship for operation of a liot air engine.

For the purpose of providing a heating jacket for the displacement cylinders, the bottom member 30 has fastened thereto spaced sheet metal casings 65 and 66 closed by end lates 67 and 68. Suitable heating insulating material, such as magnesia or asbestos indicated at 69, is positioned between the spaced casings. On one side of the displacement cylinders, the bottom member 31 is formed with a longitudinally extending slot or opening 7() beneath which is attached a gas supply pipe 72 adapted to supply a combustible fluid to the combustion space of the heating jacket. Between the displacement cylinders and the gas supply pipe 72 is lo cated an upstanding baiiie 75 which is so arranged as to cause the products of combustion to pass upwardly through channel 76 between the heat insulating casing and the bafile 75, and thence downwardly over the displacement cylinders, whereb an" effective heat interchange is effected. I1 the opposite side of the displacement cylinders from the gas supply pi e, the casing is provided with an o ning 7 extending longitudinally to provide an outlet channel 78 communicating with an oftake pipe 79, from which the products of combustion escape.

The crank case 11 is closed fluid tight by means of the covers 12 and 13. Suitable lubricating oil is ada ted to be supplied to the crank case for lu rication of the crank shaft and related parts and this lubrication is assisted by means of oil rings 80 loosely suspended :fromv portions of the crank shaft. Within the casing 13, a, suitable fly wheel 82 is pinned to an extended end of the crank shaft 16 to assist the continuity of motion of the engine. The casing 13 is provided with a pipe connection 83 connected to a pressure gage 84 and also to a threaded elbow 85 which is adapted to be placed in communication with a source of fluid pressure, such as a pump, to supply a fluid medium under pressure to the engine. Air or other suitable iluid medium is in this manner supplied to the crank case under pressure, and due to the restricted communication between the crank case and the space above the pistons within the piston cylinders, the pressure within the entire system becomes equalized. Very satisfactory results have been obtained where the pressure within the cylinders is maintained at about four atmospheres, this serving to increase the power output of the engine.

In order to connect the crank shaft to an exterior power source while maintaining the system iuid tight, a sha-ft extension 90 supported in a bearing 91 formed in an extended end of the casing 13 is connected to the crank shaft 16 by a in and slot connection indicated at 92. he casing 13 is also provided with an inwardly extending cylindrical iange 93 to which is bolted a plate 94 slidably receiving an extended end or sleeve portion ,95 of the fly wheel 82. The shaft extension 90 is provided with a collar .97 with which cooperates a fioating ring or plate 98 slidably receiving the shaft extension. Fastened at one end `to the plate 94 is a syl hon packing or bellows 99, the .other end o which is attached to the floatin -member 98. In this manner, a substantia ly iuid tight packing is produced with a minimum of frictional resistance. A pulley or gear 100 is pinned to the shaft extension 90 on the exterior of the casing, and is adapted to be connected by a belt or gear drive with a generator or other suitable work device.

In operation, assuming the parts to be as shown in Fig. 1 with t ie engine stopped, heat is supplied to the heating jacket for the displacement cylinders by igniting and burning gas supplied by pipe 72, while a cooling medium such as water is supplied to the cooling jacket 57 ofl the piston cylinders. Displacement member 35 in displacement cylinder No. 1 is in a lowermost position, and the fluid is thus displaced to the upper end of the displacement cylinder and comes in contact with the heated walls thereof. The consequent heating of the uid with resultant expansion produces a rise in pressure within 'thls displacement cylinder and also within the fluid s ace of piston cylinder No. 2. During stand y periods a balanced pressure normally exists on opposite sides of any piston 20. However, due to the heating effect, an unbalanced pressure is thus produced on opposite sides of the piston 2O in piston cylinder No. 2 tending to force this piston downwardly. At this time, the piston cylinders No. 1 and N o. 3 are in lower and upper dead center positions respectively; while pistons within piston cylinders No. 2 and N o. 4 are substantially midway between dead center positions. Therefore there is substantially no effective driving force upon pistons in piston cylinders No. 1 and No.3 at this time. The displacement member in displacement cylinder N o. 3 is in uppermost position so that the duid is displaced to the lower end thereof and consequently is maintained relatively cool. In any event, there is little heating efvfeet and consequently little unbalanced pressure operating upon piston 20 in piston cylinder No. 4. While the piston 20 in piston cylinder No. 4 is 180 degrees behind piston 2U in piston cylinder No. 2 and therefore must move .upwardly as the piston in the latter cylinder moves downwardly, nevertheless the unbalanced pressure which is effective upon piston 20 in piston cylinder N o. 2 so far exceeds the unbalanced pressure which may exist on opposite sides of piston No. 4, that an Aedective thrust is produced on piston No. 2,

tending-to start reciprocation of all the pistons with consequent rotation of the crank shaft 16.

This is true for any crank position in which two of the pistons are in substantially dead center position. When none of the pistons are in a dead center position, then an effective starting thrust will operate upon two of the pistons 20. For example, assume the crank shaft 16 to be turned slightly forward from the position shown in Fig. 1. Then the piston 20 of No. 3 cylinder will be moved past dead center and an effective driving thrust will be` produced upon piston No. 3 as well as piston No. 2. Thus irrespective of the crank position upon stopping, an effective starting thrust results upon the application of heat to the displacement cylinders. By a proper design of the parts with a view to minimizing mechanical friction, the engine may be made self-starting; in any event, only a slight turn upon the crank shaft will readily start the engine. When once started, the movement of the displacement members causes the alternate displacement of the iiuid medium from the heated end to the cooled end and vice versa, with alternate contraction and expansion thereof, to produce the driving force which operates the hotair engine.

Thus a unitary multicylinder hot air engine is provided in which the parts are compactly arranged with displacement cylinders in alignment with piston cylinders and the respective displacement members directly connected with aligned pistons. At the same time, the proper phase relation between the moving parts is provided by means of connections between each displacement c linder and an adjacent piston cylinder, so t at the respective displacement member is ninety degrees in angular advance of the iston within the communicating piston cyiinder. Uniform heating and operation of the engine is secured by means of the common heating jacket for the displacement cylinders, and the common cooling jacket for the piston cylinders.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the append,- ed claims.

What is claimed is: l

1. In a multicylinder hot air engine, a plurality of cylinders, a piston for each of said cylinders, a like number of displacement cylinders, each of said displacement cylinders being mounted in alignment with one of said first named cylinders, a displacement member for each of said displacement cylinders, rods directly connecting' each of said pistons with its aligned displacement member. a common crank shaft, a driving connection between each piston and said crank shaft, and means providinga common closed iiuidsystem for al1 said displacement cylinders and said piston cylinders, including an A,enclosing crank case for said crank shaft and pistons, and connections providing iuid communications between each displacement cylinder and an adjacent non-aligned piston cylinder.

2. In a multicylinder hot air engine comprising a plurality of cylinders, a piston for each of sald cylinders, a like number of displacement cylinders, a displacement member for each of said displacement cylinders, mechanical connections between each displacement member and one of said pistons, and passages prviding communication between each displacement cylinder and a piston cylinder other than the piston cylinder containing the piston to which its displacement member is connected, each said passage providing communication between a piston-and a displacement 'member whose positions in lthe cycle are substantially 90 apart.

3. In a multicylinder hot air engine, a plurality of piston cylinders, pistons operating therein, a crank shaft having cranks angularly spacedninety degrees apart, operative connections between Said pistons and said cranks, a plurality of displacement cylinders,

displacement members. operating therein, ya direct rod connection between each piston and an aligned displacement member, whereby each interconnected piston and displacement member operate simultaneously in the same phase, and passages providing communication between each of said displacement cylmembers therein, a positive interconnection.

independent of said crank shaft between each displacement member and a piston for simultaneous operation in the same phase, and passages providing communication between each one of said piston cylinders and one of said displacement cylinders, each said displacement cylinder containing a displacement member therein which is ninety degrees in angular advance of the piston in the said communicating piston cylinder.

5. 'In a hot air engine, a plurality of piston cylinders. pistons operating therein, a crank shaft having cranks angularly spaced ninety degrees apart about said shaft, operative connections between said pistons and said cranks, a plurality of displacement cylinders disposed in alignment with said piston cylinders, displacement members therein, partitions closing communication between the aligned displacement cylinders and piston cylinders, rods passing through said partitions directly connecting each displacement member with its aligned piston for simultaneous movement in the same phase within their respective cylinders, and passages providing communication between each displacement cylinder and anl adjacent piston cylinder not in alignment therewith, the displacement member in saiddisplacement cylinder being ninety degrees in advance of the piston in said communicating piston cylinder.

6. In a multicylinder hot air engine, an engine block having a plurality of piston cylinders formed therein, pistons operating therein, a uid tight crank case for said cylinders, a crank shaft therein having angularly spaced cranks thereon, driving connections between said crank shaft and said pistons, a plurality of displacement cylinders mounted on said block in alignment with said piston cylinders, a head for closing communication between each of said displacement cylinders and the aligned piston cylinder, rods passing through said heads interconnecting each of said pistons with the aligned displacement member, heating means for said displacement cylinders, cooling means for said piston cylinders, and connections providing fluid communication between each displacement cylinder and an adjacent non-aligned piston cylinder, such that the respective displacement member and iston of each pair of communieating cylin ers are connected substantially 90 a art.

7.. n a multicylinder hot air engine, an engine block having a plurality of piston cylin ers formed therein and also having a water jacket formed therein common to all said cylinders, pistons operating within said cylinders, said block being formed at the outer end lott each c linder with a cylindrical bore of different diameter than said cylinder bore and providing a shoulder between the said cylindrical bore and the cylinder` bore, a plurality of relatively thin walled displacement cylinders mounted over the outer ends of each of the cylindrical bores and in ali ent with the respective piston cylinders, is lacement members operating therein, hea s seating against the shoulders in said block closing communication between each displacement cylinder and the aligned piston cylinder, a rod connection directly interconnecting each piston cylinder and its aligned displacement member and passing through the respective head, a jacket surrounding the outer ends of said .displacement cylinders and providing a heatin fluid circulating space common to all said displacement cylinders, a crank shaft having cranks angularly spaced substantially 90 apart, interconnections between said pistons and said cranks, and connections providing communication between each displacein ent cylinder and a cooperating-non-aligned piston cylinder, such that the respective displacement member and piston of each pair of communicating cylinders are connected substantially 90 apart.

In testimony whereof I hereto ailix my signature.

HARRY F. SMITH. 

